Bob , Nanopowders are the latest toys for colorants. I have an article on APUG also. For strong inks formulas , you can google patent search
for banknote printing inks. Its not problem to find source , it is the problem of be able to buy small amounts. If United States produces 1100 , Europe produces 700 and Japan produces 500 amount of ink worldwide.

Raised surface is faraway less controllable than opposite and you cant load ink as much as you want. Tief- hole- druck , rotogravure process is able to hold more ink in its dots and you can control the tonal variation and strong tones with faraway more success.

I will send you an ink book and some scans of national geographic today. I decided to write an article also .

Umut